1. Field of the Invention
The present invention relates to a pulse radar device, and more particularly to a pulse radar device that transmits an electric wave, and detects the presence/absence of an object by receiving a reflection wave obtained by the reflection of the transmitted electric wave from the object, to thereby measure a distance to the detected object.
2. Description of the Related Art
In the conventional pulse radar device, a pulsed signal is periodically outputted by a transmit means. Then, a reflection pulse from an object is continuously received by a receive means, and then binary-coded by a binary coding means. A sampling means samples a binary signal at every one or plural given sampling points after the transmit timing of the transmit means; obtains a sampling value of 0 or 1; and supplies the sampling value to an adding means corresponding to the respective sampling points. The adding means adds the sampling value of 0 or 1 at every given transmit number of times of the signals by the transmit means. Upon the completion of the adding process by the given number of times, a judging means compares a normalized addition value obtained by dividing the addition values in each of the adding means by the number of times of addition with a given threshold value, judges whether or not the reflection signal from the external object exists on the basis of the comparison result, and judges the presence/absence of the external object on the basis of the judgment result (for example, refer to JP 07-722237A, page 1 and FIG. 1).
In the above-mentioned conventional device, in the case where a precision in the distance to the object is required, it is necessary to fine a sampling interval of the sampling means. In order to achieve this, a high-frequency clock is required, resulting in such a problem that the device becomes expensive. Also, there is proposed a method in which a receive wave is subjected to A/D conversion, and the distance precision is improved by the received waveform. However, a high-speed A/D converter is required, resulting as well in such a problem that the device becomes expensive.